WAI Resource: HTML 4.0 Accessibility
Improvements

WAI Makes Strides Towards Universal Web Accessibility with HTML 4.0

As part of their ongoing efforts to pursue and promote
accessibility, the Web Accessibility Initiative ([WAI]), joined forces with the W3C HTML Working
Group in the design of [HTML4.0], which
became a W3C Recommendation in December, 1997. For this latest release
of the World Wide Web's publishing language, the WAI group sought
remedies for a number of authoring habits that cause problems for
users with:

Screen readers

Screen readers intercept code being sent to a monitor and direct the output
to speech synthesis or a refreshable Braille display.

In the following sections, we look at how WAI contributions to HTML
4.0 (in conjunction with style sheets) allow authors to avoid
accessibility pitfalls even as they create more attractive,
economical, and manageable pages.

Improved structure

Highly structured documents are more accessible than those that
aren't, so HTML 4.0 has added a number of elements and attributes that
enrich document structure. The new constructs will also allow software
tools (e.g., search robots, document transformation tools, etc.)
to extract more information from these documents. The following
structural elements are new in HTML 4.0:

For structured text, the ABBR and ACRONYM elements,
in conjunction with style sheets and the
"lang" (language) attribute, will provide assistance to
speech synthesizers. The Q element identifies inline
quotations, complementing the exiting BLOCKQUOTE element.

The INS and DEL elements identify new and deleted portions
of a document (great for editors).

Several new elements (THEAD, TBODY, TFOOT, COLGROUP, and COL) have
been added to group table rows and columns
into meaningful sections. Several
new attributes ("scope", "headers", and "axes")
label table cells so that
non-visual browsers may render a table in a linear fashion, based on the
semantically significant labels.

Style sheets

HTML was not designed with professional publishing in mind; its
designers intended it to organize content, not present
it. Consequently, many of the language's presentation elements and
attributes do not always meet the needs of power page designers. To
overcome layout limitations, the W3C HTML Working Group decided not to
add new presentation features to HTML 4.0, but instead to assign the
task of presentation to style sheet languages such as Cascading Style
Sheets ([CSS1] and
[CSS2]). While style sheets are not part
of HTML 4.0 proper, HTML 4.0 is the first version of the language to
integrate them fully.

Why did the HTML Working Group adopt this strategy? For one,
experience shows that distinguishing a document's structure and its
presentation leads to more maintainable and reusable documents. Also,
by extracting formatting directives from HTML documents, authors may
design documents for a variety of users and target media in mind with
minimal changes to their original HTML documents. The same HTML
document, with different style sheets, may be tailored to color-blind
users, those requiring large print, those with braille readers, speech
speech synthesizers, hand-held devices, tty devices, etc. But style
sheets have another significant impact on accessibility. They
eliminate the need to to rely on "tricks" for achieving visual
layout and formatting effects. These tricks have the unfortunate
side-effect of making pages inaccessible.

For instance, HTML does not have an element or attribute to indent
a paragraph, so many authors have resorted to using the BLOCKQUOTE
element to indent text even when there is no quotation involved (many
visual browsers indent the content of the element). This is misleading
to non-visual users: when an audio browser encounters a BLOCKQUOTE
element, it should be able to assume that the enclosed text is a
quotation. More often than not, that assumption proves incorrect since
the element has been misused for a presentation effect.

The BLOCKQUOTE example demonstrates the misuse, for presentation
purposes, of an element intended to provide logical information. Many
similar traps can seduce HTML authors: they use tables and invisible
GIF images for layout; they use H2 or H3 to change the font size of
some text that is not a header; they use the EM element to italicize
text when in fact, EM is meant to emphasize text (often presented with
an italic font style, but rendered differently by a speech
synthesizer); they use lists for alignment, etc.

Now, style sheets will give authors a richer palette for layout and
formatting at the same time they eliminate the accessibility problems
that arise from markup abuse.

Alternate content

A picture may be worth a thousand words to some people, but others
need at least a few words to get the picture. Authors should always
complement non-textual contexts -- images, video, audio, scripts, and
applets -- with alternate text content and textual descriptions.
These are vital for visually impaired users, but extremely useful to
may others: those who browse with text-only tools, those who configure
their browsers not to display images (e.g, their modem is too slow or
they simply prefer non-graphical browsing), or for those users who are
"temporarily disabled," such as commuters who want to browse the Web
while driving to work.

In HTML 4.0, there are a host of new mechanisms for specifying
alternate content and descriptions:

As in previous versions of HTML, authors may use the "alt"
attribute to specify alternate text. As of HTML 4.0, this attribute
must be specified for the IMG and AREA elements; it is
optional for INPUT and APPLET.

The new "title" attribute gives a
short description of an image, etc.
Graphical browsers frequently pop-up this information when a
user pauses over an element with the mouse
(tool-tips), but it is equally useful to non-visual browsers.

The new "longdesc" attribute designates an external
document that gives a long description of an image, etc.

The new CAPTION element and "summary" attribute (the
TABLE element) describe a table's purpose.

In addition to the new frame elements, the NOFRAMES element
specifies content to be rendered when a browser cannot render
a frame document.

In addition to the SCRIPT element, the NOSCRIPT element
specifies content to be rendered when a browser cannot
render script content.

The "title" attribute has many accessibility-related
applications. For instance, with the new ABBR
(abbreviation) and ACRONYM elements, it may indicate the expansion text of
an abbreviation. Or it may provide a short description of
an included sound clip. Or it may provide information about
why a horizontal rule (the HR element) has been used to convey a
structural division (although authors should be sure use structural
markup as well, such as the DIV or SPAN elements).

But of all the new elements, the OBJECT element (for including
images, applets, or any type of object) is the most important for
specifying alternate content. With it, authors may specify
rich alternate content (i.e., that contains markup,
impossible with attribute values) at the same location they specify the
object to be included. When a browser cannot render the image, applet,
etc. included by an OBJECT element, it renders the OBJECT's (marked up)
content instead.

One important application of this OBJECT feature involves
client-side image maps. In HTML 4.0, the content model of the MAP
element has been expanded to allow marked up anchor (A) elements that
give the geometries of the map's active regions. When placed inside of
an OBJECT element, the textual version of the image map will only be
rendered if the graphical version cannot be. Thus, authors may
create graphical and non-graphical image maps at the same
location in their documents.

Easier navigation and orientation

Visually impaired users have tremendous difficulties browsing pages
where navigation options rely largely on graphical cues. For
instance, image maps with no textual alternatives are next to
impossible to navigate. Or link text that offers no context (e.g., a
link which simply reads "click here") is as frustrating as a road sign
that reads only "Exit" -- exit to where? Or adjacent links not
separated by non-link characters confuse screen readers, which
generally interpret them as a single link.

HTML 4.0 includes several features to facilitate navigation:

For client-side image maps, the MAP element may contain anchor
elements (A) that simultaneously specify the active regions
of the image map and provide
detailed textual explanations of links. Remember, these links
may be marked up with rich alternate descriptions of the image map.

The "title" attribute, with the A element, can
describe the nature of a link so that users may decide whether
to follow it.

The "accesskey" attribute allows users to activate links or form controls
from the keyboard.

The "tabindex" attribute allows users to use the keyboard to navigate the
links or form controls on a page in a logical sequence.

The LINK element (specified in the header of a document) together with
the "media" attribute allow user agents to load appropriate
pages for a specific target medium automatically,
making user navigation to those pages unnecessary.

Better for everyone

Investing in physical-world accessibility modifications,
(wheelchair ramps, curb cuts, etc.) has benefitted a much larger
community than those with disabilities: how often have parents with
baby carriages or cyclists appreciated these same improvements?
The benefits from accessibility innovations can similarly
be generalized to other situations:

Using style sheets with HTML instead of images for handsome text
and fancy layout can reduce download times and once widespread,
is likely to improve overall Internet performance because
of faster download times.

How do I make my pages more accessible?

The WAI group has produced a set of guidelines for page authors. The guidelines,
and related documents, describe good authoring practice in detail as
it relates to accessibility.

About the Web Accessibility Initiative

The W3C Web Accessibility Initiative is
pursuing accessibility of the Web through five primary areas of work:
addressing accessibility issues in the technology of the Web; creating
guidelines for browsers, authoring tools, and content creation;
developing evaluation and validation tools for accessibility;
conducting education and outreach; and tracking research and
development. Depending on an individual's disability (or the
circumstances in which one is browsing the Web, for instance on a
device with no graphics display capability, or in a noisy
environment), graphics, audio content, navigation options, or other
aspects of Web design can present barriers.

The WAI International Program Office (IPO) enables partnering and
coordination among the many stake-holders in Web accessibility:
industry, disability organizations, government, and research
organizations. The IPO is sponsored by the US National Science
Foundation and the Department of Education's National Institute on
Disability and Rehabilitation Research; the European Commission's TIDE
Program, and W3C industry Members including IBM/Lotus Development
Corporation, Microsoft Corporation, NCR, and Riverland
Holding. Disability and research organizations on several continents
also actively participate in the WAI.

About the World Wide Web Consortium (W3C)

The W3C was created to lead the Web to its full potential by
developing common protocols that promote its evolution and ensure its
interoperability. It is an international industry consortium jointly
run by the MIT Laboratory for Computer Science (LCS) in the USA, the
National Institute for Research in Computer Science and Control
(INRIA) in France and Keio University in Japan. Services provided by
the Consortium include: a repository of information about the World
Wide Web for developers and users; reference code implementations to
embody and promote standards; and various prototype and sample
applications to demonstrate use of new technology. To date, more than
235 organizations are Members of the Consortium.